1. Field of the Invention
The present invention relates to a conductive ball mounting method and a surplus ball removing apparatus and, more particularly, a conductive ball mounting method for forming bump electrodes by mounting conductive balls on a wiring substrate, or the like and a surplus ball removing apparatus used in this method.
2. Description of the Related Art
In the prior art, there is the method of forming the bump electrodes by mounting the solder ball on the connection pads of the wiring substrate on which the semiconductor chip, or the like is mounted, respectively. In such solder ball mounting method, as shown in FIG. 1, first, a wiring substrate 100 on which the solder balls are to be mounted is prepared. In the wiring substrate 100, connection pads 200 which are connected to buildup wirings (not shown) is provided on an upper surface side of a substrate 110, and a solder resist 300 in which opening portions 300a are provided on the connection pads 200 is formed. Also, a flux 400 is coated on the connection pads 200 respectively.
Then, as shown in FIG. 2, a mask 500 used to mount the solder balls is arranged on the wiring substrate 100. A plurality of opening portions 500a through which the solder ball is passed respectively are provided in portions which correspond to the connection pads 200 of the wiring substrate 100, in the mask 500.
Then, as also shown in FIG. 2, a large number of solder balls 600 are supplied onto the mask 500, and the solder balls 600 are moved by a brush 700 such that these balls are swept out toward one end side of the mask 500. Thus, as shown in FIG. 3, the solder balls 600 are passed through the opening portions 500a of the mask 500, and then adhered to the fluxes 400 on the connection pads 200 of the wiring substrate 100 and placed thereon. Also, the extra solder balls 600 are swept out toward one end side of the mask. Then, the wiring substrate 100 is moved downward and is separated from the mask 500.
As the technology related to the above solder ball mounting method, in Patent Literature 1 (Patent Application Publication (KOKAI) 2001-358450), it is set forth that, a chip is set to the solder ball mounting apparatus equipped with the ball alignment mask, then the solder balls are put down through the through holes in the ball alignment mask by jolting the apparatus main body with the hand, and then the extra solder balls are recovered in the ball storage groove which is provided on the ball guide frame.
Also, in Patent Literature 2 (Patent Application Publication (KOKAI) 2006-173195), it is set forth that, a large number of solder balls are supplied onto the mask which is put on the wafer, then the solder balls are moved by the filling head with the sweeping member such that the solder ball is arranged in the opening portions of the mask respectively, and then the solder balls still remaining on the mask are swept outward the mask by the removing head having the soft squeegee and are removed from the mask.
Also, in Patent Literature 3 (Patent Application Publication (KOKAI) 2002-184803), it is set forth that, in the absorbing arrangement method in which a plurality of conductive balls are absorbed by the absorbing head, and the conductive balls are arranged collectively on respective electrodes, the normal conductive balls are supplemented in the ball unfilled locations on the electrodes, and in the ball surplus locations, an arrangement defect is removed and then the normal conductive balls are supplemented there.
In the above steps in FIG. 2 and FIG. 3 in the prior art, even though a large number of solder balls 600 on the mask 500 are moved toward one end side of the mask 500 by the brush 700, in many cases the extra solder balls 600 remain somewhat in the area where the opening portions 500a are arranged on the mask 500.
Therefore, as shown in FIG. 4, while the wiring substrate 100 is moved downward and is separated from the mask 500, in some cases the solder balls 600 still remaining on the mask 500 drop onto the wiring substrate 100 through the opening portions 500a of the mask 500. Further, because the mask 500 is jolted, sometimes the solder balls 600 which are swept out toward one end side of the mask 500 roll along in the opening portion 500a side of the mask 500, and then drop onto the wiring substrate 100.
When the extra solder balls 600 on the mask 500 drop onto the wiring substrate 100, the extra solder ball 600 (indicated with a black mark) is mounted in vicinity of the normal solder balls 600 which are arranged on the connection pads 200 on the wiring substrate 100. Therefore, in a situation that the bump electrodes are formed by melting the solder balls, extra-large bump electrodes which protrude higher than other bump electrodes are formed on the connection pads on which the extra solder ball 600 is mounted respectively, which acts as a cause of a reduction of yield of the wiring substrate.
There is the method of removing the surplus balls on the wiring substrate by human work, but this method needs the very troublesome work. As a result, the method capable of removing effectively the surplus balls is desired earnestly.